2 * Copyright (C) 2006-2009 Red Hat, Inc.
4 * This file is released under the LGPL.
7 #ifndef __DM_LOG_USERSPACE_H__
8 #define __DM_LOG_USERSPACE_H__
10 #include <linux/dm-ioctl.h> /* For DM_UUID_LEN */
13 * The device-mapper userspace log module consists of a kernel component and
14 * a user-space component. The kernel component implements the API defined
15 * in dm-dirty-log.h. Its purpose is simply to pass the parameters and
16 * return values of those API functions between kernel and user-space.
18 * Below are defined the 'request_types' - DM_ULOG_CTR, DM_ULOG_DTR, etc.
19 * These request types represent the different functions in the device-mapper
20 * dirty log API. Each of these is described in more detail below.
22 * The user-space program must listen for requests from the kernel (representing
23 * the various API functions) and process them.
25 * User-space begins by setting up the communication link (error checking
26 * removed for clarity):
27 * fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
28 * addr.nl_family = AF_NETLINK;
29 * addr.nl_groups = CN_IDX_DM;
31 * r = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
32 * opt = addr.nl_groups;
33 * setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &opt, sizeof(opt));
35 * User-space will then wait to receive requests form the kernel, which it
36 * will process as described below. The requests are received in the form,
37 * ((struct dm_ulog_request) + (additional data)). Depending on the request
38 * type, there may or may not be 'additional data'. In the descriptions below,
39 * you will see 'Payload-to-userspace' and 'Payload-to-kernel'. The
40 * 'Payload-to-userspace' is what the kernel sends in 'additional data' as
41 * necessary parameters to complete the request. The 'Payload-to-kernel' is
42 * the 'additional data' returned to the kernel that contains the necessary
43 * results of the request. The 'data_size' field in the dm_ulog_request
44 * structure denotes the availability and amount of payload data.
48 * DM_ULOG_CTR corresponds to (found in dm-dirty-log.h):
49 * int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
50 * unsigned argc, char **argv);
52 * Payload-to-userspace:
53 * A single string containing all the argv arguments separated by ' 's
55 * A NUL-terminated string that is the name of the device that is used
56 * as the backing store for the log data. 'dm_get_device' will be called
57 * on this device. ('dm_put_device' will be called on this device
58 * automatically after calling DM_ULOG_DTR.) If there is no device needed
59 * for log data, 'data_size' in the dm_ulog_request struct should be 0.
61 * The UUID contained in the dm_ulog_request structure is the reference that
62 * will be used by all request types to a specific log. The constructor must
63 * record this association with the instance created.
65 * When the request has been processed, user-space must return the
66 * dm_ulog_request to the kernel - setting the 'error' field, filling the
67 * data field with the log device if necessary, and setting 'data_size'
73 * DM_ULOG_DTR corresponds to (found in dm-dirty-log.h):
74 * void (*dtr)(struct dm_dirty_log *log);
76 * Payload-to-userspace:
77 * A single string containing all the argv arguments separated by ' 's
79 * None. ('data_size' in the dm_ulog_request struct should be 0.)
81 * The UUID contained in the dm_ulog_request structure is all that is
82 * necessary to identify the log instance being destroyed. There is no
85 * When the request has been processed, user-space must return the
86 * dm_ulog_request to the kernel - setting the 'error' field and clearing
87 * 'data_size' appropriately.
92 * DM_ULOG_PRESUSPEND corresponds to (found in dm-dirty-log.h):
93 * int (*presuspend)(struct dm_dirty_log *log);
95 * Payload-to-userspace:
100 * The UUID contained in the dm_ulog_request structure is all that is
101 * necessary to identify the log instance being presuspended. There is no
104 * When the request has been processed, user-space must return the
105 * dm_ulog_request to the kernel - setting the 'error' field and
106 * 'data_size' appropriately.
108 #define DM_ULOG_PRESUSPEND 3
111 * DM_ULOG_POSTSUSPEND corresponds to (found in dm-dirty-log.h):
112 * int (*postsuspend)(struct dm_dirty_log *log);
114 * Payload-to-userspace:
119 * The UUID contained in the dm_ulog_request structure is all that is
120 * necessary to identify the log instance being postsuspended. There is no
123 * When the request has been processed, user-space must return the
124 * dm_ulog_request to the kernel - setting the 'error' field and
125 * 'data_size' appropriately.
127 #define DM_ULOG_POSTSUSPEND 4
130 * DM_ULOG_RESUME corresponds to (found in dm-dirty-log.h):
131 * int (*resume)(struct dm_dirty_log *log);
133 * Payload-to-userspace:
138 * The UUID contained in the dm_ulog_request structure is all that is
139 * necessary to identify the log instance being resumed. There is no
142 * When the request has been processed, user-space must return the
143 * dm_ulog_request to the kernel - setting the 'error' field and
144 * 'data_size' appropriately.
146 #define DM_ULOG_RESUME 5
149 * DM_ULOG_GET_REGION_SIZE corresponds to (found in dm-dirty-log.h):
150 * uint32_t (*get_region_size)(struct dm_dirty_log *log);
152 * Payload-to-userspace:
155 * uint64_t - contains the region size
157 * The region size is something that was determined at constructor time.
158 * It is returned in the payload area and 'data_size' is set to
161 * When the request has been processed, user-space must return the
162 * dm_ulog_request to the kernel - setting the 'error' field appropriately.
164 #define DM_ULOG_GET_REGION_SIZE 6
167 * DM_ULOG_IS_CLEAN corresponds to (found in dm-dirty-log.h):
168 * int (*is_clean)(struct dm_dirty_log *log, region_t region);
170 * Payload-to-userspace:
171 * uint64_t - the region to get clean status on
173 * int64_t - 1 if clean, 0 otherwise
175 * Payload is sizeof(uint64_t) and contains the region for which the clean
176 * status is being made.
178 * When the request has been processed, user-space must return the
179 * dm_ulog_request to the kernel - filling the payload with 0 (not clean) or
180 * 1 (clean), setting 'data_size' and 'error' appropriately.
182 #define DM_ULOG_IS_CLEAN 7
185 * DM_ULOG_IN_SYNC corresponds to (found in dm-dirty-log.h):
186 * int (*in_sync)(struct dm_dirty_log *log, region_t region,
189 * Payload-to-userspace:
190 * uint64_t - the region to get sync status on
192 * int64_t - 1 if in-sync, 0 otherwise
194 * Exactly the same as 'is_clean' above, except this time asking "has the
195 * region been recovered?" vs. "is the region not being modified?"
197 #define DM_ULOG_IN_SYNC 8
200 * DM_ULOG_FLUSH corresponds to (found in dm-dirty-log.h):
201 * int (*flush)(struct dm_dirty_log *log);
203 * Payload-to-userspace:
208 * No incoming or outgoing payload. Simply flush log state to disk.
210 * When the request has been processed, user-space must return the
211 * dm_ulog_request to the kernel - setting the 'error' field and clearing
212 * 'data_size' appropriately.
214 #define DM_ULOG_FLUSH 9
217 * DM_ULOG_MARK_REGION corresponds to (found in dm-dirty-log.h):
218 * void (*mark_region)(struct dm_dirty_log *log, region_t region);
220 * Payload-to-userspace:
221 * uint64_t [] - region(s) to mark
225 * Incoming payload contains the one or more regions to mark dirty.
226 * The number of regions contained in the payload can be determined from
227 * 'data_size/sizeof(uint64_t)'.
229 * When the request has been processed, user-space must return the
230 * dm_ulog_request to the kernel - setting the 'error' field and clearing
231 * 'data_size' appropriately.
233 #define DM_ULOG_MARK_REGION 10
236 * DM_ULOG_CLEAR_REGION corresponds to (found in dm-dirty-log.h):
237 * void (*clear_region)(struct dm_dirty_log *log, region_t region);
239 * Payload-to-userspace:
240 * uint64_t [] - region(s) to clear
244 * Incoming payload contains the one or more regions to mark clean.
245 * The number of regions contained in the payload can be determined from
246 * 'data_size/sizeof(uint64_t)'.
248 * When the request has been processed, user-space must return the
249 * dm_ulog_request to the kernel - setting the 'error' field and clearing
250 * 'data_size' appropriately.
252 #define DM_ULOG_CLEAR_REGION 11
255 * DM_ULOG_GET_RESYNC_WORK corresponds to (found in dm-dirty-log.h):
256 * int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
258 * Payload-to-userspace:
262 * int64_t i; -- 1 if recovery necessary, 0 otherwise
263 * uint64_t r; -- The region to recover if i=1
265 * 'data_size' should be set appropriately.
267 * When the request has been processed, user-space must return the
268 * dm_ulog_request to the kernel - setting the 'error' field appropriately.
270 #define DM_ULOG_GET_RESYNC_WORK 12
273 * DM_ULOG_SET_REGION_SYNC corresponds to (found in dm-dirty-log.h):
274 * void (*set_region_sync)(struct dm_dirty_log *log,
275 * region_t region, int in_sync);
277 * Payload-to-userspace:
279 * uint64_t - region to set sync state on
280 * int64_t - 0 if not-in-sync, 1 if in-sync
285 * When the request has been processed, user-space must return the
286 * dm_ulog_request to the kernel - setting the 'error' field and clearing
287 * 'data_size' appropriately.
289 #define DM_ULOG_SET_REGION_SYNC 13
292 * DM_ULOG_GET_SYNC_COUNT corresponds to (found in dm-dirty-log.h):
293 * region_t (*get_sync_count)(struct dm_dirty_log *log);
295 * Payload-to-userspace:
298 * uint64_t - the number of in-sync regions
300 * No incoming payload. Kernel-bound payload contains the number of
301 * regions that are in-sync (in a size_t).
303 * When the request has been processed, user-space must return the
304 * dm_ulog_request to the kernel - setting the 'error' field and
305 * 'data_size' appropriately.
307 #define DM_ULOG_GET_SYNC_COUNT 14
310 * DM_ULOG_STATUS_INFO corresponds to (found in dm-dirty-log.h):
311 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_INFO,
312 * char *result, unsigned maxlen);
314 * Payload-to-userspace:
317 * Character string containing STATUSTYPE_INFO
319 * When the request has been processed, user-space must return the
320 * dm_ulog_request to the kernel - setting the 'error' field and
321 * 'data_size' appropriately.
323 #define DM_ULOG_STATUS_INFO 15
326 * DM_ULOG_STATUS_TABLE corresponds to (found in dm-dirty-log.h):
327 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_TABLE,
328 * char *result, unsigned maxlen);
330 * Payload-to-userspace:
333 * Character string containing STATUSTYPE_TABLE
335 * When the request has been processed, user-space must return the
336 * dm_ulog_request to the kernel - setting the 'error' field and
337 * 'data_size' appropriately.
339 #define DM_ULOG_STATUS_TABLE 16
342 * DM_ULOG_IS_REMOTE_RECOVERING corresponds to (found in dm-dirty-log.h):
343 * int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
345 * Payload-to-userspace:
346 * uint64_t - region to determine recovery status on
349 * int64_t is_recovering; -- 0 if no, 1 if yes
350 * uint64_t in_sync_hint; -- lowest region still needing resync
353 * When the request has been processed, user-space must return the
354 * dm_ulog_request to the kernel - setting the 'error' field and
355 * 'data_size' appropriately.
357 #define DM_ULOG_IS_REMOTE_RECOVERING 17
360 * (DM_ULOG_REQUEST_MASK & request_type) to get the request type
362 * Payload-to-userspace:
363 * A single string containing all the argv arguments separated by ' 's
365 * None. ('data_size' in the dm_ulog_request struct should be 0.)
367 * We are reserving 8 bits of the 32-bit 'request_type' field for the
368 * various request types above. The remaining 24-bits are currently
369 * set to zero and are reserved for future use and compatibility concerns.
371 * User-space should always use DM_ULOG_REQUEST_TYPE to acquire the
372 * request type from the 'request_type' field to maintain forward compatibility.
374 #define DM_ULOG_REQUEST_MASK 0xFF
375 #define DM_ULOG_REQUEST_TYPE(request_type) \
376 (DM_ULOG_REQUEST_MASK & (request_type))
379 * DM_ULOG_REQUEST_VERSION is incremented when there is a
380 * change to the way information is passed between kernel
381 * and userspace. This could be a structure change of
382 * dm_ulog_request or a change in the way requests are
383 * issued/handled. Changes are outlined here:
384 * version 1: Initial implementation
385 * version 2: DM_ULOG_CTR allowed to return a string containing a
386 * device name that is to be registered with DM via
389 #define DM_ULOG_REQUEST_VERSION 2
391 struct dm_ulog_request
{
393 * The local unique identifier (luid) and the universally unique
394 * identifier (uuid) are used to tie a request to a specific
395 * mirror log. A single machine log could probably make due with
396 * just the 'luid', but a cluster-aware log must use the 'uuid' and
397 * the 'luid'. The uuid is what is required for node to node
398 * communication concerning a particular log, but the 'luid' helps
399 * differentiate between logs that are being swapped and have the
400 * same 'uuid'. (Think "live" and "inactive" device-mapper tables.)
403 char uuid
[DM_UUID_LEN
];
404 char padding
[3]; /* Padding because DM_UUID_LEN = 129 */
406 uint32_t version
; /* See DM_ULOG_REQUEST_VERSION */
407 int32_t error
; /* Used to report back processing errors */
409 uint32_t seq
; /* Sequence number for request */
410 uint32_t request_type
; /* DM_ULOG_* defined above */
411 uint32_t data_size
; /* How much data (not including this struct) */
416 #endif /* __DM_LOG_USERSPACE_H__ */
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